70,000 Deaths and 3,000 Stillbirths Caused by Infections
New research funded by the World Health Organization (WHO) estimates
that 20.1 million individuals were infected with hepatitis E virus (HEV)
genotypes 1 and 2 across 9 world regions in 2005. According to findings
available in the April issue of Hepatology,
a journal published by Wiley-Blackwell on behalf of the American
Association for the Study of Liver Diseases, there were 3.4 million
symptomatic cases, 70,000 deaths, and 3,000 stillbirths from HEV that
year in countries throughout Asia and Africa.
Unlike hepatitis virus B and C strains that lead to chronic disease
states, HEV causes acute illness. Previous studies show HEV genotypes 1
and 2 specifically infect humans, and are associated with large
outbreaks in developing countries where sanitation conditions are poor.
There is evidence that HEV increases mortality risk among pregnant
women. While a safe and effective HEV vaccine has been developed, it has
not been widely implemented.
“Our study represents the first attempt to estimate the annual global
impact of hepatitis E,” said lead author Dr. David Rein of the social
science research organization NORC at the University of Chicago.
Estimates were created by modeling the disease burden of HEV genotypes 1
and 2 in the 9 regions, representing 71% of the world’s population.
Based on published evidence the team—a collaboration between researchers
from NORC, WHO and RTI International—also estimated annual incidence of
infection to determine symptomatic, asymptomatic, and mortality cases.
The team determined that the prevalence pattern of HEV was consistent
across the regions, with the largest incident increase occurring in
those between the ages of 5 and 20 years. The average age of infection
was 17 years with the lowest age of infection in North Africa (8 years)
and highest in East Asia (21 years).
Of the more than 20 million people infected with HEV, 61% of the cases
occurred in East and South Asia, two regions which also accounted for
65% of deaths from HEV. Researchers also noted that North Africa
accounted for 14% of all global HEV infections, but only 8.3% of
symptomatic cases and 8% of deaths, which the authors attribute to the
younger average age of infection in that region.
The authors caution there are limitations to the study which only
estimated incidence of HEV genotypes 1 and 2, leaving out genotype 3
that prevalently occurs in Europe and the U.S., and genotype 4. “Future
HEV estimates should include genotypes 3 and 4 to provide a complete
picture of the global burden of HEV,” concludes Dr. Rein.
